2nd pivot for VPI 3D

It is easier to visualize what is happening when you have the kit in your hands and no matter how articulate our words are, they fall short.  I will try.  Visualize a tripod, that is a platform with three feet.  The first foot is the unipivot of the VPI arm which you are familiar with.  The second foot is the second pivot, think of it as an outrigger like might exist on a canoe, which supports the tonearm and prevents it from tipping on the unipivot. The third pivot is the stylus resting in the groove of the record.  We have just defined a plane in space.  The azimuth is very precisely defined by the outrigger or second pivot.  So adding pressure or weight to the second pivot will not change the azimuth as it did before, because the second pivot will prevent movement.  The three points of contact fix the arm in the plane defined by those three points. So with the kit installed, the side to side rotation about the axis of the unipivot is eliminated. The arm is stable like a gimbal bearing tonearm.  The trick is to optimize the amount of pressure exerted on the second piovt as azimuth is fixed and stable.  When you see it the simplicity will become apparent.  What is amazing is how such a simple idea can have such an extraordinary effect.

Thanks Bill....I'll give it a try.

I ordered the kit recently. Still waiting on delivery but I'll chime in here when I know something.  

The interesting thing to me is, this seems to increase the effective mass of the tonearm by adding friction in the horizontal plane. Which should make the tonearm more amenable to a range of carts with different compliances. and in addition the 'extra' mass is adjustable depending how much you tighten the pivot, meaning the arm's mass can be fine tuned to the cartridge. And even more, you get a more precise AND stable way to adjust the azimuth to boot. That all seems kind of brilliant. 

Different in application, but similar to what Basis does.  Basis put a second bearing inside the unipivot well and use a counterweight with one empty side to balance the arm against the second bearing.  The result is a unipivot arm that looks and feels like a fixed bearing design.  Absolutely no wobble.  

Well I received my dual pivot assembly and got it set up on my Aries 1. I’m quite happy with it and I agree that it’s a worthwhile upgrade to the normal "single pivot" arm. There’s a clear improvement in focus and precision in space, and it isn’t subtle or imaginary. With this mod I feel like I have a better sense of what the cartridge is really capable of. Also the azimuth is blessedly easy to adjust with a little twist of the included hex wrench. That takes a lot of the mystery out of the process for me. So good that I ordered a second one for another arm wand.